Steerable device and system

ABSTRACT

A system includes a steerable device, such as a sheath or shaft, having proximal and distal ends. The steerable device includes an elongated body having a proximal section, a steering section, and a distal tip. Control wires are routed through the body and connected at or near the distal end of the steerable device. The system further includes a control unit to which the proximal end of the steerable device is functionally connected. In one embodiment, the control unit includes an actuator connected to one control wire and a biasing force generating device connected to a second control wire. The steering section is controllably manipulated by the control unit to facilitate steering of the distal tip of the steerable device as the steerable device is advanced through tortuous passageways of a patient&#39;s body.

FIELD OF THE INVENTION

In general, the present invention is directed to systems suitable foruse in medical procedures, and in particular, to medical systems thatinclude a steerable device that is controlled by a control unit at theproximal end thereof.

BACKGROUND OF THE INVENTION

Endoscopes and imaging catheters are widely used in many medicalprocedures for viewing areas of bodily organs, cavities, passageways,etc. Generally, such imaging devices include an elongate sheath orsimilar structure wherein optical fibers are arranged both fortransmitting illumination light to the distal end of the sheath toilluminate a viewing field, and for carrying an optical image back to aviewing port or camera. One or more lenses may be positioned on thedistal end of the imaging device to focus the optical image received by,or the illumination cast by the instrument.

In many applications, it is desirable that the distal portion of theimaging device be “steerable”, bendable or maneuverable from theproximal end of the device to facilitate guidance of the device throughtortuous or furcated anatomical passageways. Additionally, the abilityto bend the device at or near its distal end may enable the operator tovisually scan an expanded viewing area by bending or otherwisemanipulating the distal end of the device Second, the ability tomaneuver the tip makes it easier to guide the tip of the device properlythrough the often highly branched and convoluted passageways near organssuch as the coronary arteries of the heart or the branched ducts of thebiliary tree.

In order to effect and control the deflection of the distal tip of animaging device, many designs have been introduced that incorporateeither two opposed control wires to control bending in one plane or fourwires evenly spaced to control bending in two perpendicular planes.These control wires run the length of the device and terminate at thedistal end of the steerable region or at the distal tip. The proximalend of each control wire is functionally connected to a separate drum orspool rotated by a dedicated electrical or fluid motor for linearlyadvancing and retracting the control wire in relation to the device. Inoperation, when one of the control wires is pulled proximally byrotation of the drum or spool, the distal tip of the device bends at thesteerable region toward the retracted wire.

SUMMARY OF THE INVENTION

Embodiments of the present invention are directed to systems thatinclude steerable devices that maintain full steerability while reducingthe total number of motors or actuators needed to bend the distal tip ofthe device with 2-way articulation in one plane or 4-way articulation inmore than one plane. In accordance with one embodiment of the presentinvention, a system is provided that includes a steerable device, suchas a sheath or shaft, and a control unit. The steerable device includesfirst and second control wires connected at or near the distal end thatextend from the proximal end thereof. The control unit includes anactuator connected to the proximal end of the first control wire and abiasing force generator connected to the proximal end of the secondcontrol wire.

In accordance with aspects of the present invention, a system isprovided. The system includes an elongate flexible device havingproximal and distal ends and a longitudinal axis. The device includes asteerable section and a distal tip disposed at the distal end. Thedevice is bendable at the steerable section for deflecting the distaltip in at least a first and a second direction. The system furtherincludes at least first and second control wires having proximal anddistal ends. The first and second control wires are routed through theflexible device. The distal ends of the first and second control wiresare coupled at or near the distal end of the flexible device, wherebymovement of the first control wire proximally deflects the distal tip inthe first direction and movement of the second control wire proximallydeflects the distal tip in the second direction. The distal tip isbiased in the first direction by force applied to the first controlwire.

In accordance with another aspect of the present invention, a system isprovided. The system includes a device having proximal and distal endsand being deflectable between a series of positions, and first andsecond control wires having proximal and distal ends. The movement ofthe control wires causes the distal end to be deflected between theseries of positions. The system further includes a control unitfunctionally connected to the proximal end of the device. The controlunit including at least one actuator connected to the proximal end ofthe first or second wire and at least one force generating deviceconnected to the proximal end of the other of the first or secondcontrol wire. The force generating device applies a first force on thefirst or second wire when the distal end is deflected to a firstposition, and applies a second force different than the first force onthe first or second control wire when the distal tip is bent to a secondposition.

In accordance with another aspect of the present invention, a system isprovided. The system includes an elongated device having a proximal end,a bendable distal section, and a distal end. The system also includesfirst and second control wires routed through the device. The distalends of control wires are connected at or near the distal end of thedevice. The system further includes means for applying a biasing forceon the first or second control wire in the proximal direction thereof.

In accordance with yet another aspect of the present invention, a systemis provided. The system includes a steerable device including anelongate flexible body having proximal and distal ends, and a bendablesection positioned near the distal end. The bendable section ismanipulatable in at least one plane. the steerable device furtherincludes at least first and second control wires having proximal anddistal ends. The first and second wires are routed through the body. Thedistal ends of the first and second wires are coupled at or near thedistal end of the body. The system further includes a control unitfunctionally connected to the proximal end of the device body. Thecontrol unit includes an actuator connected to the proximal end of thefirst control wire and a variable force generating device connected tothe proximal end of the second control wire. The variable forcegenerating device is capable of urging the second control wire in theproximal direction.

In accordance with yet another aspect of the present invention, anendoscopic system is provided. The system includes a shaft defining acentralized lumen and having proximal and distal ends, a bendablesection at or near the distal end of the shaft for selectively orientingthe distal end of the shaft, at least first and second control wirespassed through the shaft and connected at or near the distal end of theshaft, and a control unit that controls the orientation of the distalend. The control unit includes an actuator that is connected to theproximal end of the first control wire and a biasing force generatorthat is connected to the proximal end of the second control wire.

In accordance with still another aspect of the present invention, acontrol device for use with a steerable medical device is provided. Thecontrol device includes at least one pair of control wires fordeflecting a distal end of the medical device, a housing configured forreceiving the pair of control wires, a drive member carried by thehousing for pulling one control wire of the pair of control wires, and abiasing force generator carried by the housing. The biasing forcegenerator is connected to other control wire of the pair of controlwires. The control device further includes an actuator operably coupledto the drive member for effecting movement of the drive member.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of thisinvention will become more readily appreciated by reference to thefollowing detailed description, when taken in conjunction with theaccompanying drawings, wherein:

FIG. 1 illustrates one exemplary embodiment of a system formed inaccordance with aspects of the present invention;

FIG. 2 is a cross sectional view of one embodiment of a steerabledevice, in particular, an endoscope in accordance with one embodiment ofthe present invention;

FIG. 3 is an exploded cross-sectional view of one embodiment of aflexible sheath section of the endoscope of FIG. 2;

FIG. 4 is a cross sectional view of the steerable section of theendoscope shown in FIG. 2;

FIG. 5 is a cross sectional view of the steerable section taken alonglines 5-5 in FIG. 4;

FIG. 6 is a partial cross sectional view of an alternative embodiment ofthe proximal section of the endoscope shown in FIG. 2;

FIGS. 7A-7C are sequential views of deflecting the distal end of anendoscope by a control unit formed in accordance with one embodiment ofthe present invention;

FIG. 8 is a partial view of an alternative embodiment of a control unitincluding a manually controlled actuator formed in accordance with oneembodiment of the present invention;

FIG. 9 illustrates an alternative embodiment of a biasing forcegenerating device suitable for use in the control unit; and

FIG. 10 illustrates an exemplary embodiment of a control unit, such as acontrol handle, formed in accordance with aspects of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will now be described with reference to thedrawings where like numerals correspond to like elements. Embodiments ofthe present invention are directed to systems having steerable devicesof the type broadly applicable to numerous medical applications in whichit is desirable to insert the device into a body lumen or passageway.Embodiments of the steerable devices may include such features asillumination and visualization capabilities, for endoscopically viewinganatomical structures within the body when insertable therein. As such,embodiments of the present invention can be used for a variety ofdifferent diagnostic and interventional procedures, includingcolonoscopy, upper endoscopy, bronchoscopy, thoracoscopy, laparoscopyand video endoscopy, etc., and are particularly well suited fornegotiating tortuous passageways of the human body. Although exemplaryembodiments of the present invention will be described hereinafter asincluding endoscopes or endoscopic imaging devices, it will beappreciated that aspects of the present invention have wide application,and may utilize other medical devices, such as steerable imaging andnon-imaging catheters (e.g., angioplasty catheters) or other flexiblesteering devices. Accordingly, the following descriptions andillustrations herein should be considered illustrative in nature, andthus, not limiting the scope of the present invention, as claimed.

FIG. 1 illustrates one exemplary embodiment of a system 20 constructedin accordance with aspects of the present invention. The system 20includes a steerable device 24 having a proximal end 26 and a distal end28. The steerable device 24 includes an elongated shaft-like body 36comprising a proximal section 40, a steering section 44, and a distaltip 48 disposed at the distal end 28 of the sheath 24. The system 20further includes a control unit 50 to which the proximal end 26 of thesteerable device 24 is functionally connected. As will be described inmore detail below, the orientation of the steering section 44 ismanipulated by the control unit 50 to facilitate steering of the distaltip 48 of the device 24 as the device 24 is advanced through tortuouspassageways of the patient's body.

One suitable embodiment of the steerable device 24 will now be describedin greater detail. As described above, the steerable device 24 includesa proximal section 40, a steering section 44, and a distal tip 48. Asbest shown in FIGS. 1 and 2, the proximal section 40 of the device body36 begins at the proximal end 26 of the device 24 and extends along amajority of the device body's total length. The proximal section 40 maybe of any suitable construction and made of any suitable material.

In one embodiment, the proximal section 40 includes a proximal cap 56and a distal cap 60 interconnected by a flexible tubular sheath 64, asbest shown in FIG. 2. The sheath 64 may be constructed of any suitablematerial that allows the device body 36 to navigate the tortuous pathsof the patient's body but does not axially deform or compress, such aspolyurethane, polypropylene, nylon, ABS or other biocompatible plastics.If desired, the sheath 64 may include a braid to increase its crushstrength and/or its torsional rigidity.

In the embodiment shown in FIG. 3, the proximal and distal caps 56 and60 are tubular members of circular cross-section constructed of anysuitable biocompatible material, such as stainless steel orpolyurethane, polypropylene, nylon, ABS or other biocompatible plastics.The proximal cap 56 is configured at its distal end with a reduceddiameter portion 66. Similarly, the distal cap 60 is configured at itsproximal end with a reduced diameter portion 68. Both reduced diameterportions 66 and 68 are sized and configured for insertion into the openends of the tubular sheath 64 for connection therewith. The proximal anddistal caps 56 and 60 define centralized passageways 70 and 74,respectively, concentrically arranged with the central lumen 76 definedby the tubular sleeve 64 for forming a contiguous central passagewaythrough the proximal section 40 when assembled. As will be described inmore detail below, the contiguous central passageway may allow foroptics, working devices, fluid channels, or the like, to be routed tothe distal tip of the device.

In one embodiment, the caps 56 and 60 are sized and configured such thatwhen the reduced diameter portions 66 and 68 of the caps 56 and 60,respectively, are inserted into the ends of the tubular sheath 64 duringassembly, the caps 56 and 60 are retained thereto by a friction fit.Alternatively, the ends of the sheath 64 may be coupled to the caps 56and 60 by heat bonding, adhesive bonding, fasteners, or other techniquesknown in the art. In one embodiment, the components may be dimensionedsuch that when the reduced diameter portions 66 and 68 of the caps 56and 60 are inserted into the ends of the tubular sheath 64, and abuttedagainst the shoulders formed thereby, the outer surface of the sleeve 64is flush with the remaining portion of the caps 56 and 60, therebyforming a section of the device 24 having a substantially constantdiameter, as best shown in FIG. 2.

Returning now to FIG. 3, the proximal and distal caps 56 and 60 furtherdefine in their walls axially extending guide lumens 84 disposedradially offset from the longitudinal axis A of the device foraccommodating smooth passage of control wires, as will be described inmore detail below. In one embodiment, the caps 56 and 60 define firstand second guide lumens 84A and 84B disposed 180 degrees from oneanother, the purpose of which will be described in more detail below.The distal cap 60 is further provided with a joint section 88 in theform of a recessed slot. The joint section 88 is sized and configuredfor connecting the distal end of the proximal section 40 to the proximalend of the steering section, as will be described in detail below.

While the proximal section 40 has been illustrated and described has anassembly of end caps interconnected by a tubular sheath, it will beappreciated that the proximal section may have other suitableconstructions. For example, the proximal section 40 may be an integrallyformed tube section 140 defining a central passageway 176 and aplurality of offset guide lumens 184 formed in the tube walls forpassage of control wires, as best shown in FIG. 6. In this embodiment,the integrally formed proximal section 140 may form a joint section (notshown) for connection to the steering section.

As was described above, the distal end of the proximal section 40 isconnected to the proximal end of the steering section 44 at the distalregion of the device 24, as best shown in FIG. 1. The steering section44, in use, allows the distal tip 48 to be selectively steered,manipulated, or bent in one or more planes by action occurring at theproximal end of the device 24. Referring now to FIG. 4, there is shownone exemplary embodiment of the steering section 44. As best shown inFIG. 4, the steering section 44 includes an articulated joint 92 coveredby an elastic sheath 96. In one embodiment, the articulated joint 92includes an articulated series of ring shaped joint segments 100A-100E,although other numbers of joint segments may be used. Adjacent jointsegments are connected with each other by pins 104 so that each of theadjacent ring joint segments can rotate about the pins 104. In theembodiment shown, all of the pins 104 are parallel to one another so asto lie in a common plane. As such, the steering section 44 is capable ofbending in a common plane, and as a result, produces 2-way articulationwhen manipulated by control wires, as will be described in more detailbelow.

Each joint segment 100 further defines a centralized passageway 110concentrically arranged with the central passageway of the proximalsection when assembled so that optics, working devices, fluid channels,or the like, may be routed to the distal tip 48 of the device. Eachjoint segment 100 may further defines a plurality of axially extendingguide lumens 114 disposed radially offset from the longitudinal axis ofthe device 24. The guide lumens 114 can be formed in the walls of thejoint segments 100 and are aligned with the guide lumens of the proximalsection. In the embodiment shown, the joint segments 100 include firstand second guide lumens 114A and 114B that are concentrically arrangedwith the distal cap section guide lumens 84A and 84B for the passage ofcontrol wires, as will be described below. It will be appreciated thatthe number of guide lumens formed in the joint segments and theirorientation effects the direction of bending of the steering section 44.In the embodiment shown in FIGS. 4-6, the steering section 44 isbendable in a single plane. As such, the guide lumens 114A and 114B arearranged 180 degrees apart and approximately 90 degrees from the pivotaxis 118 of the pins 104, as best shown in FIG. 5.

While the steering section 44 has been illustrated and described as aseries of ring-shaped joint segments 100 hingedly connected, it will beappreciated that other steering sections that are bendable either in oneor more planes may be practiced with the present invention. For severalnon-limiting examples of steerable sections that may be practiced withthe present invention, please see co-pending U.S. application Ser. No.10/811,781, filed Mar. 29, 2004, U.S. Pat. No. 5,846,183, U.S.application No. ______, entitled “Video Endoscope” and filedconcurrently herewith as Attorney Docket No. BSEN-1-23550, and U.S. Pat.No. 6,699,179 B2, which are hereby incorporated by reference.Additionally, although the joint segments 100 of the articulation joint92 shown in FIG. 4 are generally circular in shape, it will beappreciated that other shapes could be used. For example, square jointsegments as well as triangular or pentagonal cross sections, etc., couldalso be used to form the articulation joint.

Returning to FIG. 4, the device 24 may also include a distal tip 48,which is connected to the distal end of the steering section 44. In oneembodiment, the proximal end of the distal tip 48 is provided with ajoint section 130 for connecting to the distal end of the steeringsection 44. In the embodiment shown, the joint section 130 is a recessedslot positioned at the proximal end of the distal tip 48 for connectionwith the steering section 44. The joint segment 130 is sized andconfigured for receiving the distal joint segment 100A in a seatingmanner, as shown best in FIG. 2. Once seated, the distal tip 48 may thenbe adhesively secured, welded, bonded, or otherwise connected to thedistal end of the steering section 44.

As best shown in FIG. 2, the device 24 further includes a number ofcontrol wires 140 that extend longitudinally through the device 24 fromthe proximal end 26 of the device 24 and terminate distally of thesteering section 44. The control wires 140 terminate either at thedistal end of the articulation joint 92 or at the distal tip 48. In theembodiment shown, the control wires 140 terminate with enlarged heads142 at their distal ends, which are positioned distally of the end jointsegment 100A. Alternatively, the control wires 140 may be attached tothe distal tip 48 via the receipt of the enlarged heads into a pair ofcounterbored apertures disposed within the proximal end of the distaltip 48. As an alternative to interfacing the wires to the distal tip 48in the aforementioned techniques, the distal ends of the control wires140 may be directly welded to the distal tip 48 or affixed thereto byany other suitable means which maintains the control wires 140 in thedesired orientation. Examples of other such affixation methods includecrimping or knotting the distal ends of the control wires 140 to preventthe same from sliding through the joint segment guide lumens 84. In theembodiment shown, the device 24 includes first and second control wires140A and 140B.

As the first and second control wires 140A and 140B extend proximally,the control wires pass through the joint segment guide lumens 114A and114B formed in the steering section 44, the cap guide lumens 84A and 84Bformed in the proximal section 40, and protrude out of the proximal end26 of the device 24. It should be noted that the guide lumens 114 and 84are suitably sized so that the control wires 140A and 140 B may beadvanced and retracted smoothly without binding. As will be described indetail below, the proximal ends of the control wires 140A and 140 B arefunctionally connected to the control unit, which can effect bending ofthe distal end 28 by selective movement of the control wires 140A and140B.

The control wires 140A and 140B may be of the pull or tension type, andare preferably made of a non-stretching material, such as stainlesssteel, braided polymer fibers, or the like. The control wires 140A and140B are preferably carried in stainless steel or plastic sleeves 146through the proximal section 40 so as to be protected from and to notinterfere with the components routed through the central passageway ofthe device 24. As such, the guide lumens 84A and 84B of the distal andproximal caps 56 and 60 are configured for receiving the ends of theprotective sleeve 146, as best shown in FIG. 3. While not shown, it willbe appreciated that the protective sleeves 146 may extend from theproximal end of the control wires 140A and 140B to the distal end of thecontrol wires, or along any portion thereof. In one embodiment of theinvention, the control wires 140A and 140B are Bowden cables and arecoated with a lubricant, such as silicone, in order to reduce friction,and the protective sleeves 146 include a lubricous liner, such as HDPE.

Returning to FIG. 2, to effect bending of the distal end 28 of thedevice 24 to facilitate device steering, the control wires 140A and 140Bmay be sequentially pulled in the proximal direction, thus imparting atensioning force thereon. Such a tensioning force on one of the controlwires deflects or bends the distal end 28 of the device 24 at thesteering section 44 in the direction of the tensioned control wire asknown in the art. As such, selectively pulling the control wires 140Aand 140B can steer the distal tip 48 as the device 24 is advancedthrough the passageways of the patient. The device 24 just described isonly one of many steerable devices that may be practiced with thepresent invention. Accordingly, any suitable steerable device having atleast two opposing control wires may be practiced with the presentinvention.

Returning now to FIG. 1, the system 20 further includes a control unit50 functionally connected to the proximal end of the device 24. Theconnection between the proximal end 26 of the device 24 and the controlunit 50 allows the control wires 140A and 140B to be freely advanceableand retractable relative thereto and may prohibit contaminates or debrisfrom entering the central passageway. In one embodiment, the proximalend of the cap 56 may include a joint section (not shown) or may beconnected directly to a conventional fitting for connection to thehousing (not shown) of the control unit 50. Such connections are wellknown in the medical device art, and thus, will not be described indetail here.

In accordance with one aspect of the present invention, embodiments ofthe system 20 are configured for reducing the number of motors oractuators needed to effect 2-way articulation of the distal end 28 ofthe device 24 in at least one plane. To that end, one illustrativeembodiment of the control unit 50 will now be explained in more detail.Referring to FIG. 1, the control unit 50 includes at least one actuator160 operatively mounted therein and at least one biasing forcegenerating device 166. The proximal end of the first control wire 140Ais functionally connected to the actuator 160 so that operation of theactuator 160 allows for the linear advancement and retraction of thecontrol wire 140A with respect to the device body 36 to effect bendingthereof as described above. The proximal end of the second wire 140B isconnected to the biasing force generating device 166 such that thebiasing force generating device imparts a biasing force against thesecond control wire 140B when the second control wire is pulled in theopposite direction (i.e. distally). In one embodiment, the proximal endof the second control wire 140B may be detachably connected to thebiasing force generating device is a selective manner. Accordingly,during use, the second control wire 140B may be detached or decoupledfrom the biasing force generating device, if desired.

While the illustrative embodiment of FIG. 1 shows the first control wire140A being connected to the actuator 160 and the second control wire140B being connected to the biasing force generating device 166, it willbe appreciated that the first control wire 140A may be connected to thebiasing force generating device 166 while the second control wire 140Bis connected to the actuator 160.

In the embodiment shown in FIG. 1, the actuator is a spool 180 rotatablydriven by a motor 184, such as a DC reversible stepper motor or servomotor. Alternatively, the spool 180 may be controllably driven by othercontrollable electrical motors or fluid motors known in the art. Inother embodiments, the actuator 160 may be other powered devices, suchas a hydraulically/pneumatically powered linear actuator, a motorizedlinear screw mechanism, motorized rack and pinion, etc. If powered, theactuators may receive appropriate control signals from an input device,such as a joystick controller, as known in the art.

Alternatively, manually operated structure, such as a pivoting lever,rotating knob, etc., that are capable of advancing and retracting thefirst control wire 140A may be used. In one embodiment, as shown best inFIG. 8, the actuator 160 is a manual, linear slide mechanism equippedwith a handle 170 graspable by the physician or assistant during use. Inone embodiment, the actuator 160 may be incorporated into a manualcontrol handle, which may also house the biasing force generatingdevice. FIG. 10 illustrates an embodiment of a manual control handle 186that includes a control knob 188 for effecting movement of the firstwire 140A and a biasing force generating device 166 carried in thecontrol handle 186 and connected to the second wire 140B.

As was described above, the proximal end of the second control wire 140Bis connected to the biasing force generating device 166. The biasingforce generating device 166 is anchored to a portion of the control unitat 190. The biasing force generating device 166 is configured to imparta biasing force against the second control wire 140B when the secondcontrol wire 140B is pulled distally, such as when the distal end 28 ofthe device 24 is bent in the opposite direction by proximal movement ofthe control wire 140A. In the embodiment shown in FIG. 1, the biasingforce generating device 166 is a tension spring, e.g., a coil spring,although other devices configured by those skilled in the art forapplying a biasing force against the movement of the control wire 140Bin the distal direction, such as fluid or elastic dampers, leaf springs,shock absorbers, etc., may be practiced with the present invention. Onesuch example is illustrated in FIG. 9, in which a sliding piston 194 anda compression spring 196 are utilized to generate a biasing forceagainst the wire 140B when the control wire 140B is pulled in theopposite direction of the device 166. It will be appreciated that thespring force of the spring or other biasing force generating devices maybe either variable or constant.

The device 24, and more particularly, the control wires 140A and 140B,are connected to the control unit 50 in such a manner that allows thecontrol unit 50 to effect 2-way articulation of the distal tip 48 in acommon plane. In one embodiment, the second control wire 140B ispre-tensioned or pre-loaded prior to connection to the biasing forcegenerating device 166 such that the distal tip 48 of the device 24achieves a desired angle of deflection in the direction of the secondcontrol wire 140B, as best shown in FIG. 7A. To compensate for thedistal tip 48 being deflected or bent to the position shown in FIG. 7A,the actuator 160 may be activated in a suitable manner to allow forwardor distal movement of the first control wire 140A if connected prior tothe second control wire 140B, or alternatively, the first control wire140A may be connected to the actuator 160 after the connection of thesecond control wire 140B to the biasing force generating device 166.

To effect bending or deflection of the distal tip 48 in the directionopposite of that shown in FIG. 7A, such as to straighten the device body36 to the position shown in FIG. 7B, the first control wire 140A islinearly translated proximally by the actuator 160. As the first controlwire 140A is pulled proximally by the actuator 160, the distal tip 48 ofthe device 24 deflects in the direction of the pulled control wire 140A,which in turn, causes the second control wire to be pulled distallyagainst the biasing force generated by the biasing force generatingdevice 166.

The first control wire 140A may continue to be pulled proximally by theactuator 160 against the continued biasing force of the device 166 toanother deflection position, such as the one shown in FIG. 7C. It willbe appreciated that the distal tip 48 may be deflected by an anglegreater than the angle of deflection shown in FIG. 7A, if desired.

To return the distal tip 48 to the straightened position as shown inFIG. 7B, the actuator 160 is actuated in a suitable manner to allow thefirst control wire 140A to be linearly translated in the forward, i.e.,distal, direction, which allows the biasing force imparted against thesecond control wire 140B by the biasing force generating device 166 topull the second control wire 140B proximally so that the device 24straightens. To return the distal tip 48 to the position shown in FIG.7A, the actuator 160 continues to allow the first control wire 140A tobe moved distally by the biasing force applied to the second controlwire 140B by the biasing force generating device 166 until the distaltip 140A has achieved the position shown in FIG. 7A. Thus, the amount ofinitial distal tip deflection defines one deflection limit or maximumangle of deflection of the distal tip in one direction.

As was briefly described above, in one embodiment of the presentinvention, the device 24 may include endoscopic features for use inmedical procedures that require illumination and/or visualization. Tothat end, a fiber optic imaging bundle and one or more illuminationfibers may extend through the central passageway from the proximal end26 to the distal end 28 of the device body 36. Alternatively, the device24 can be configured as a video endoscope with a miniaturized videocamera, such as a CCD or CMOS camera, which transmits images to a videomonitor by a transmission cable or by wireless transmission. Optionally,the device may include one or two instrument channels routed through thecentral passageway that may also be used for insufflation or irrigationor the application of aspiration.

While the system 20 described above and illustrated herein included asteerable device having a distal end that is bendable or deflectable inone common plane, it will be appreciated that aspects of the presentinvention will also benefit systems that utilize steerable deviceshaving a distal end that is bendable or deflectable in two perpendicularplanes through the activation of four control wires disposed equidistantaround the perimeter of the device. Several non-limiting examples of4-way steerable devices that may be practiced with the present inventionor several steering sections that my be incorporated into devices thatmay be practiced with the present invention are shown in U.S.application Ser. No. 10/811,781, filed Mar. 29, 2004, U.S. Pat. No.5,846,183, and U.S. Pat. No. 6,699,179 B2, which are hereby incorporatedby reference. In such systems that utilize a steerable device that isdeflectable in two perpendicular planes by manipulating four controlwires, the control unit 50 includes first and second actuators 160 andfirst and second biasing force generating devices 166 connected to thefirst and third and second and fourth control wires, respectively.

While embodiments of the system 20 has been described above andillustrated herein as including endoscopes or endoscopic imagingdevices, steerable catheters, such as an angioplasty catheter, acatheter with sensing probes, or any other flexible or steerable devicewhich one may wish to introduce into a place which is difficult to reachmay be used. Such devices need not be confined to the medical field.Other important applications include the introduction of tools (forinspection, adjustment, or repair) in industrial applications, such asengines or other machines. For inspection purposes, fiber optics may becarried by these devices. One such device that may be practiced withembodiments of the present invention is a steerable boroscope. Thus,although the illustrative embodiments of the present invention aredescribed primarily in terms of an endoscope or endoscopic imagingdevice, embodiments of the present invention have many otherapplications.

While the preferred embodiments of the invention have been illustratedand described, it will be appreciated that various changes can be madetherein without departing from the spirit and scope of the invention.For example, it is envisioned that embodiments of the present inventionmay be used with an odd number of control wires, such as a three controlwire system where one wire is connected to a biasing force generator andthe other control wires each being connected to an actuator. It istherefore intended that the scope of the invention be determined fromthe following claims and equivalents thereof.

1. A system, comprising: a steerable device having proximal and distalends, the device including at least a first and second control wireconnected at or near the distal end and extending from the proximal endthereof; and a control unit that controls the orientation of the distalend by selectively pulling the control wires in the proximal direction,wherein the control unit includes a selectively controlled actuator thatis connected to the proximal end of the first control wire and a biasingforce generator that is connected to the proximal end of the secondcontrol wire.
 2. The system of claim 1, wherein the biasing forcegenerator is connected to the proximal end of the second control wire toexert a continuous force on the second wire such that the distal end ofthe steerable device is maintained in a curved state by the secondcontrol wire and straightened by the application of a pulling force onthe first control wire by the actuator.
 3. The system of claim 1,wherein the biasing force generator is a spring.
 4. The system of claim1, wherein the steerable device is selected from the group consisting ofan endoscope, a catheter, a sheath, and a shaft.
 5. A system,comprising: an elongate flexible device having proximal and distal endsand a longitudinal axis, the device including a steerable section and adistal tip disposed at the distal end, the device being bendable at thesteerable section for deflecting the distal tip in at least a first anda second direction; and at least first and second control wires havingproximal and distal ends, the first and second control wires routedthrough the flexible device, the distal ends of the first and secondcontrol wires being coupled at or near the distal end of the flexibledevice, whereby movement of the first control wire proximally deflectsthe distal tip in the first direction and movement of the second controlwire proximally deflects the distal tip in the second direction; whereinthe distal tip is biased in the first direction by force applied to thefirst control wire.
 6. The system of claim 5, further comprising firstand second lumens defined by the flexible device, the first and secondlumens being radially offset from the longitudinal axis of the flexibledevice, wherein the first and second control wires are routed throughthe first and second lumens, respectively.
 7. The system of claim 5,further comprising a biasing force generating device coupled to theproximal end of the first control wire, a portion of the biasing forcegenerating device being anchored against movement relative to the firstcontrol wire.
 8. The system of claim 7, wherein the biasing forcegenerating device is a spring.
 9. The system of claim 8, wherein thespring rate of the spring is variable or constant.
 10. The system ofclaim 7, wherein the first control wire is connected to the biasingforce generating device such that the distal tip is bent to a selectedangle of deflection about the steerable section.
 11. The system of claim5, wherein the distal end is bendable in at least one plane.
 12. Thesystem of claim 5, wherein the flexible device is selected from thegroup consisting of an endoscope, a catheter, a sheath, and a shaft. 13.A system, comprising: a device having proximal and distal ends, thedistal end being deflectable between a series of positions; first andsecond control wires having proximal and distal ends, the movement ofthe control wires causing the distal end to be deflected between theseries of positions; a control unit functionally connected to theproximal end of the device, the control unit including at least oneactuator connected to the proximal end of the first or second wire andat least one force generating device connected to the proximal end ofthe other of the first or second control wire, wherein the forcegenerating device applies a first force on the first or second wire whenthe distal end is deflected to a first position, and applies a secondforce different than the first force on the first or second control wirewhen the distal tip is bent to a second position.
 14. The system ofclaim 13, wherein the distal end is deflected from the first position tothe second position by actuation of the actuator.
 15. The system ofclaim 14, wherein the distal end automatically returns to the firstposition from the second position by actuation of the actuator.
 16. Thesystem of claim 15, wherein the device has a non-deflected state and adeflected state, the distal end being biased away from the non-deflectedstate.
 17. The system of claim 13, wherein the device is selected fromthe group consisting of an endoscope, a catheter, a sheath, and a shaft.18. A system, comprising: an elongated device having a proximal end, abendable distal section, and a distal end; first and second controlwires routed through the device, the distal ends of which are connectedat or near the distal end of the device; and means for applying abiasing force on the first or second control wire in the proximaldirection thereof.
 19. The system of claim 18, wherein the first orsecond control wire is pre-loaded, resulting in distal end bending ofthe device in one direction.
 20. The system of claim 19, wherein thedevice is selected from the group consisting of an endoscope, acatheter, a sheath, and a shaft.
 21. The system of claim 18, wherein themeans for applying a biasing force is a spring.
 22. A system,comprising: a steerable device including an elongate flexible bodyhaving proximal and distal ends, a bendable section positioned near thedistal end, the bendable section being manipulatable in at least oneplane, and at least first and second control wires having proximal anddistal ends, the first and second wires routed through the body, thedistal ends of the first and second wires being coupled at or near thedistal end of the body; and a control unit functionally connected to theproximal end of the device body, the control unit including an actuatorconnected to the proximal end of the first control wire and a variableforce generating device connected to the proximal end of the secondcontrol wire, the variable force generating device capable of urging thesecond control wire in the proximal direction.
 23. The system of claim22, wherein the bendable section includes an articulation section. 24.The system of claim 23, wherein the articulation section comprising aplurality of segments interconnected via joints.
 25. The system of claim22, wherein the actuator is manually actuated.
 26. The system of claim22, wherein the actuator is motorized.
 27. The system of claim 22,wherein the steerable device is selected from the group consisting of anendoscope, an imaging endoscope, a catheter, an imaging catheter, asheath, and a shaft.
 28. An endoscopic system, comprising: a shaftdefining a centralized lumen and having proximal and distal ends; abendable section at or near the distal end of the shaft for selectivelyorienting the distal end of the shaft; at least first and second controlwires passed through the shaft and connected at or near the distal endof the shaft; and a control unit that controls the orientation of thedistal end, the control unit including an actuator connected to theproximal end of the first control wire and a biasing force generatorconnected to the proximal end of the second control wire.
 29. A controldevice for use with a steerable medical device, comprising: at least onepair of control wires for deflecting a distal end of the medical device;a housing configured for receiving the pair of control wires; a drivemember carried by the housing for pulling one control wire of the pairof control wires; a biasing force generator carried by the housing, thebiasing force generator being connected to other control wire of thepair of control wires; and an actuator operably coupled to the drivemember for effecting movement of the drive member.